"""Configuration loading and output directory setup helpers."""

from pathlib import Path

from omegaconf import DictConfig, OmegaConf

from .constants import DEFAULT_SUBJECTS


def load_config(cfg_path: str | Path) -> DictConfig:
    """Load a YAML config into an OmegaConf DictConfig."""
    return OmegaConf.load(cfg_path)


def resolve_subjects(cfg: DictConfig) -> list[int]:
    """Resolve subjects from config or fall back to defaults."""
    subjects = cfg.get("subjects", list(DEFAULT_SUBJECTS))
    return list(subjects)


def prepare_output_dir(cfg: DictConfig) -> Path:
    """Create output directory and persist an exact config snapshot."""
    out_dir = Path(cfg.out_dir)
    out_dir.mkdir(parents=True, exist_ok=True)
    OmegaConf.save(cfg, out_dir / "config.yaml")
    return out_dir